Tube drawing apparatus



Dec. 20, 1966 J. J. PONCAR 3,292,407

TUBE DRAWING APPARATUS Filed June 18, 1964 VENTOR. l2 IN 4: 6' ll Qg y, BY JOHN J. PONCAR JA 7W1 ATTORNEYS United States Patent 3,292,407 TUBE DRAWING APPARATUS John J. Poncar, Chagrin Falls, Ohio, assignor of one-half to Bruce B. Krost Filed June 18, 1964, Ser. No. 376,036 20 Claims. (Cl. 72-283) My invention relates to apparatus for drawing tubes, such as metal tubes, to reduced size.

An object of my invention is to provide improved apparatus for the drawing of a tube, as for example, a copper, brass or aluminum tube, from its initial diameter and wall thickness to a subsequent diameter and wall thickness.

Another object is the provision for improved means for lubricating a tube as it is being drawn through the throat of a die in the reduction of the tube.

Another object is the provision of an improved means for cooling or reducing the heat in a tube as it is being drawn through a die in the process of reducing the size of the tube.

Another object is the provision of apparatus for tube drawing which facilitates both rapid and efficient drawing of a metal tube.

Another object is the provision of a combination of means cooperating to obtain improved quality in a tube being drawn. 7

Another object is the provision for combining a sink die with a draw die in a manner to obtain improved results.

Another object is the provision of an arrangement of dies arranged in tangent and in axial alignment for effecting subsequent steps in the reduction of the tube being drawn.

Another object is the provision of improved means for both lubricating and cooling a tube as it is drawn.

Another object is the provision of a unique structural arrangement which produces superior results in a novel and highly useful manner.

Another object is the provision of improved tube drawing apparatus which obviates and minimizes the disadvantages and limitations of prior apparatus of this general class.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing, in which:

FIGURE 1 is a longitudinal sectional view of a preferred form of my improved tube drawing apparatus and showing a metal tube being drawn therethrough from left to right;

FIGURE 2 is a cros-sectional view, drawn to half the scale of FIGURE 1, looking in the direction of the arrows 2-2 of FIGURE 1;

FIGURE 3 is a cross-sectional view, drawn to half the scale of FIGURE 1, and looking in the direction of the arrows 33 of FIGURE 1;

FIGURE 4 is a cross-sectional view, drawn to half the scale of FIGURE 1, taken through the line 44 of FIG- URE 1;

FIGURE 5 is a cross-sectional view, drawn to half the scale of FIGURE 1, and taken thorugh the line 5-5 of FIGURE 1; and

FIGURE 6 is a cross-sectional view, drawn to half the scale of FIGURE 1, and taken through the line 6-6 of FIGURE 1.

My apparatus includes a die holder 12 which in turn is carried by the supporting portion 11 of appropriate tube drawing equipment, such tube drawing equipment being well known. Equipment of this general class is shown,

for example, in US. Patents No. 2,196,646 and No.

"ice

2,306,712. The die holder 12 has a flange or shoulder portion 12A at the rearward end thereof. Extending axially through this flange portion 12A is a round opening 12B.

Located within and carried by the die holder 12 is a first or sink die 13 of annular form, which die 13 has a round axially disposed throat or central opening 13A extending therethrough. The die 13 also has an inclined or sloping entrance wall 13B which leads or extends to the throat 13A.

Also located in and carried by the die holder 12 is a second or draw die 15. This draw die 15 abuts the flange portion 12A of the die holder 12 which prevents the die 15 from moving to the right in FIGURE 1 relative to the die holder. The die 15 has a throat or central opening 15A extending axially therethrough. The die 15 also has a sloping entrance wall 15B which extends in a slope on the entrance side toward the throat 15A. The die 15 snugly fits the internal wall of the cylindrical bore of the holder 12 so as to be maintained in fixed position relative to the axis of the holder. The die 13, however, may have a somewhat sloppy or loose fit within the bore of the holder 12. For example, there may be a space on the order of -inch between the outer circumference of the die 13 and the inner wall of the holder 12 in which the die 13 is positioned. This slight space permits the die 13 to move up and down slightly so as to accurately axial- 1y align the throat 13A of die 13 with the throat 15A of die 15. The pull of a tube being drawn through the respective throats of the two dies tends to axially align the die 13 with the die 15. This obviates fine mechanical adjustment of the axis of the die 13 relative to the axis of the die 15.

Interposed between the dies 13 and 15 and carried by the holder 12 is a spacer ring or member 14. This spacer .ring is in non-rotative engagement with the inner wall of the holder 12 and a suitable means may be provided for preventing rotation of the spacer ring 14 relative to the holder 12, such as by a key or pin 19 illustrated in FIG- URE 5. A metal tube 20, as for example,"a copper, brass or aluminum tube, moves from left to right through the aligned dies as seen in FIGURE 1. A suitable pulling mechanism which seizes the end of the tube on the right end thereof and pulls it forcibly through the throats of the aligned dies from left to right as seen in FIGURE 1. In moving from left to right, the tube 20 having the initial diameter and wall thickness shown on the left-hand side of FIGURE 1 first meets the sloping entrance wall 13B and is then cammingly urged inward along the inclined wall 13B to the throat 13A. The tube 20 at this :location has progressively formed thereon a tapered portion 20a complementing the sloping wall 13A of die 13. After the tube passes through the throat or cylindrical opening 13A, the tube has a straight portion 20B having a reduced outer diameter. By reason of the reduction of the outer diameter of the tube, the wall of the portion 20B may be slightly thicker than the wall of the initial portion 20 prior to entering the die 12. The portion 20B of the tube then meets the sloping or inclined entrance wall 15B of die 15 and is then cammingly urged inwardly to the throat or cylindrical opening 15A of die 15. The tube portion which leaves the die 15, that is, the tube portion on the right-hand side of FIGURE 1, is denoted by the reference character 200,

There is an annular space 16 which is provided around the exterior of the wall of tube portion 20B and intermediate of the throats 13A and 15A taken in an axial direction. The opposed faces of the dies 13 and 15 and the inner wall of the ring 14 together provide wall means which, with the exterior of the tube portion 20B, provide an enclosed chamber 16 outwardly of the intermediate tube portion 203. In other words, the annular space 16 3 is confined by the dies 13 and 15, the ring 14 and the outer surface of tube portion 20B.

Extending through the supporting portion 11, the holder 12 and the ring 14 is an inlet conduit 17. This inlet conduit is preferably formed of aligned openings through the respective parts 11, 12 and 14 so as to provide communication with the annular space or chamber 16. The inlet conduit 17 is near the uppermost portion of the apparatus as seen in FIGURE 1.

There is provided an outlet conduit 18 providing communication with the annular space or chamber 16, this 'outlet conduit 18 being located near the bottom of the apparatus as seen in FIGURE 1. This outlet conduit 18' is also made up of aligned openings in the supporting portion 11, the holder 12 and the ring 14. FIGURE 6 illustrates the manner in which the outlet conduit 18 is formed by the aligned openings. The inlet conduit 17 above is similarly formed by aligned openings.

Centrally located within the tube being drawn through the die apparatus is a drawing plug denoted generally by the reference character 21. This plugs 21 preferably is of the floating type which is located within the tube and maintained within the dies. The plug 21 has a forward drawing or sizing portion 22.- The outer peripheral wall of the forward portion 22 is cylindrical and closely engages the inner wall of the tube as it is drawn through the throat 15A of the die 15. The diameter of the forward portion 22 is less than the internal diameter of the throat 15A and the difference between these diameters reduces the wall thickness of the tube and sizes the same to the thickness of the portion 20C leaving the die apparatus. The internal diameter of the throat 15A is less than the internal diameter of the throat 13A, whereby the thickness of the tube wall of portion 20C is less than the thickness of the tube wall of the portion 20B.

The plug 21 has an enlarged head or rearward portion 24. This enlarged head 24 is of a maximum diameter generally greater than the internal diameter of the throat 13A of die 13. In other words, the maximum diameter of the enlarged head 24 is sufficient to resist movement of the head 24 through the throat 13A of die 13 along with the tube as it is being drawn therethrough. This difference in diameter causes the plug 21 to be held back and not moved to the right with the tube as it is being drawn to the right in FIGURE 1 enough to maintain its position relative to the dies as illustrated in FIGURE 1. The enlarged head or rearward portion 24 may have a frusto-conical or angular forward surface as illustrated or it may be disposed on a radius, that is, be partially ball-shaped. Both such types of enlarged heads of drawing plugs are well known. The forward sloping face of the enlarged portion 24 slides relative to the inner wall of the tube 20, and particularly relative to the portion 20A thereof, as the tube is forcibly drawn throughthe die 13 to the right in FIGURE 1. The pressure or force of the contact between the tube 20 and the enlarged portion 24 is preferably much less than exists between the tube 20 and forward portion 22 by the proper dimensioning of the plug relative to the dies. Thus, lubricant for example on the inner tube wall may adhere to the tube wall as it goes over or around the enlarged portion 24.

The forward or sizing portion 22 of the plug is connected to the enlarged or rearward portion 24 by a rod 'or connecting portion 23. The diameter of the portion 23 is less than the diameter of the forward portion 22 and, of course, less than the diameter of the rearward portion 24. This smaller diameter of the portion 23 results portion 24. This inner annular space 27 accommodates the material, such as dirt, fouled lubricant and metal particles, scraped from the inner wall of the tube by the forward portion 22 and permits such material to collect within the space 27. Vent means, such as a longitudinal passageway 26, is provided through or alongside of the enlarged head 24 to permit such material collected in the space 27 and building up under pressure therein to escape or be vented rearwardly into the tube 20 rather than being forced or squeezed between the inner wall of the tube portion 20C and the outer cylindrical wall of the forward portion 22., Other arrangements for collecting and venting, or permitting the escape of, material scraped from the inner wall of the tube by the plug as the tube is drawn through the die are shown and described in my US. Patent No. 3,006,460 issued October 31, 1961. Reference is made to that patent and its disclosure incorporated by reference herein for that feature of the drawing plug.

Also, the space 27 and vent means 26 permit liquid soap-lubricant or oil, disposed on the inner wall of tube 20 prior to meeting or engaging the plug (on the left in FIGURE 1) and leaking or drawing forwardly on the tube wall past or around the enlarged head 24 into the space 27, to be recirculatedor returned by permitting it to escape or flow back through the vent means 26 to the rear of the plug. This aids in maintaining good lubrication of the inner wall of the tube.

Preferably the connecting portion 23 has a threaded end portion which extends through the enlarged head 24 and a nut 25 is threadably secured to the threaded end of this rod extending rearwardly from the connecting portion 23. This nut 25 firmly secures the head portion 24 to the connecting portion 23 and thus holds the assembly of plug parts 22, 23 and 24 together.

A suitable liquid, as for example, a thin oil of appropriate composition, is introduced under pressure into the annular space or chamber 16 through the inlet conduit 17. A pump (not shown) communicating with a reservoir (not shown) of such liquid delivers liquid through the inlet conduit 17 into the space or chamber 16. This liquid fills the space or chamber 16 and is maintained under pressure therein by the force of the liquid delivered under pressure thereto as described. A limited escape of the liquid within the space or chamber 16 may be permitted through the outlet conduit 18 provided with a suitable valve and which permits the escaped liquid to be returned through suitable conduits to the said reservoir (not shown). The pressure within the space or chamber 16 may be regulated by adjusting the amount of liquid that may escape through the outlet conduit 18 in the well-known manner. The liquid may be a lubricant, such as oil, and also may function as a coolant. Such liquids having an appropriate composition for both lubricant and cooling are well known.

By having the space or chamber 16 filled with the liquid as described, the outer wall of the portion 20B1extending longitudinally between the respective throats of the dies has applied thereto the liquid so as to both cool the tube and lubricate the outer wall surface thereof. As,

7 small space between the outer wall of the tube and the inclined wall surface 15B and throat 15A, thus to provide a very thin film of the liquid as a lubricant on the outer wall of the tube and facilitate its passage through the die 15.

The circulation of liquid through the space or chamber 16 may be provided, and in fact increased, by adjusting the rate of flow of liquid under pressure through the inlet conduit 17 and the escape thereof through the outlet conduit 18. This liquid flowing downwardly through the space or chamber 16 and around the outer wall of the tube portion 20B toward the outlet conduit 18 tends to cool or extract heat from the tube wall. The liquid, acting both as a lubricant and as a coolant, is confined and does not leak or flow about the die apparatus but is maintained within the space or chamber 16 except as a very fine film or coating thereof may pass through the throat A on the outer wall of the tube portion 200, leaving the die apparatus.

It is to be understood that the spacer ring 14 is but one way of obtaining a sufiicient amount of open space to provide a chamber for accommodating the liquid be tween the die throats. The force of the die 13 to the right under the urging of the tube being pulled to the right is such as to firmly press the die 13 against the ring 14 which, in turn, is pressed firmly against the die 15. Thus, there is a good seal which confines the liquid within the annular space or chamber 16. Other arrangements for obtaining the improved results that I have obtained may be provided by following the teaching of the present disclosure but which may embody modifications and substitutions of equivalents.

I have here produced a new combination of elements and features which produces a superior quality tube with efficiency and economy of operation.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing description.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. Apparatus for the drawing of a metal tube from an initial size to reduced size comprising the combination of a first die, the throat of said first die having an internal diameter size to reduce the external diameter of said tube of initial size as the tube is drawn therethrough, a second die, the throat of said second die having an internal diameter less than the internal diameter of said first die throat to further reduce the external diameter of said tube of initial size, a holder for holding said dies in alignment with said second die following said first die in the order of travel of the tube being drawn therethrough, the throats of said dies being spaced from each other to provide an outer annular space longitudinally of said tube and around the exterior of the tube between the die mouths, means for introducing fluid lubricant into said outer annular space to apply the same to the exterior of the tube for lubricating the same prior to entering the throat of the second die, and a drawing plug positoned in said dies and concentrically of said throats to be floatingly disposed in the tube being drawn forwardly along the common axis of said throats, said plug having a rearward portion having a maximum external diameter of a size so related to the internal diameter of the first die throat as to resist being pulled forwardly along said common axis through the first die with the tube being drawn, said rearward portion being unconnected to external or other restraint against axial movement relative to said dies and by said resistance to being pulled through said first die determining the axial location of said rearward portion relative to said first die, said plug having a forward portion positionable Within the second die throat and within the tube being drawn, said forward portion supporting the tube wall and sizing the internal diameter of the tube drawn through the second die, said plug having an intermediate portion joining said forward and rearward portions and having a diameter less than the diameter of said forward portion to provide an inner annular space within the tube between said forward and rearward portions, said intermediate portion determining the axial distance between said forward portion and rearward portion of the plug to determine the location of the said forward portion of the plug relative to said second die in accordance with the location of the rearward portion of the plug as determined by the :said resistance to being pulled forwardly through said first die, said rearward portion having a vent extending the-realong for permitting material scraped from the inner wall of the tube by the plug and accumulating in said inner annular space to escape rearwardly of the plug.

2. Apparatus as claimed in claim 1 and including means for inducing a flow of said fluid lubricant through said outer annular space by providing for escape of said fluid lubricant therefrom and thereby induce cooling of the tube between said first and second dies as the tube moves to said second die.

3. Apparatus for drawing of a metal tube from an initial size to reduced size comprising the combination of first die means for first reducing the external diameter of the tube from its initial diameter as the tube is drawn therethrough, second die means for further reducing the external diameter of the said tube as the said tube is drawn therethrough, said first and second die means being serially arranged in axial alignment, chamber means located between said first and second die means for accommodating lubricant therein, said chamber means being externally of a tube being drawn through the first and second die means to supply lubricant to the exterior of the tube prior to its entry into said second die means, and drawing plug means adapted to be positioned in a said tube passing through said first and second die means to float therewith in accordance with the forward movement of the tube along the common axis of the first and second die means, said drawing plug means including head means, sizing means, connecting means and vent means, said head means being adapted to be positioned internally of the tube and having an external diameter sufiicient to resist passing forwardly through the first die means as the tube passes forwardly over said head means and through the first die means to reduce the external diameter of the tube to the internal diameter of the first die means, said sizing means having an external diameter less than the internal diameter of the second die means and adapted to be positioned internally of the tube within the second die means to size the tube through the cooperative interaction of the sizing means and the second die means as the tube is drawn therethrough, said connecting means connecting said sizing means to said head means for maintaining the position of said sizing means relative to saidsecond die means, the location of said head means along said common axis as determined by the said resistance to passing forwardly through said first die means determining such corresponding location of the sizing means along said common axis, said connecting means having an external diameter less than the external diameters of said sizing means and of said head means to provide, an inner annular space within the tube intermediate of said head means and sizing means to accommodate material scraped from the interior wall of the tube by said sizing means as the tube is drawn through the second die means, said vent means being extended along said head means to permit said material accommodated in said inner annular space to pass rearwardly therefrom into said tube rearwardly of the head means as the tube is drawn forwardly.

4. Apparatus as claimed in claim 3 and including conduit means for introducing said lubricant under pressure into said chamber means and permitting escape thereof from said chamber means to provide circulation of the lubricant for cooling said tube.

spaced an axial distance apart to provide an annular space intermediate said die throats outwardly of said tube being drawn from said sink die to said draw die, holding means for holding said sink die and dimensioned relative to said sink die to permit lateral displacement of said sink die relative to the axis of said draw die for facilitating axial alignment of the sink die by the pull of the tube being drawn forwardly through the series of sink die and draw die, confining means for confining said open space to provide with the outer wall of said tube a chamber, conduit means for introducing fluid lubricant into said chamber to cover with lubricant the outer wall of said tube intermediate of said die throats, and a drawing plug adapted to be positioned in said tube and fioatingly maintained in said dies to cooperate therewith in the drawing of the tube, said drawing plug being unrestrained against forward movement with said tube by external means, said drawing plug having a forward portion adapted to be positioned in working location within said tube radially inwardly of said draw die and leaving an outer diameter proportioned to the inner diameter of the draw die throat for the required reduction in the thickness of the wall of the tube by the working of the tube wall between said forward portion and said draw die, said drawing plug having a rearward portion adapted to be positioned within said tube adjacent the said sink die at the entrance to the throat thereof and having an outer diameter proportioned to the inner diameter of the sink die for resisting forward movement of the drawing plug with the tube through the sink and draw dies, said rearward portion and forward portion being interconnected within said tube to determine said working location of the forward portion in said draw die in accordance with the positioning of said rearward portion by the said resistance to forward,

movement thereof.

6. Apparatus as claimed in claim and in which said conduit means includes outlet means for permitting lu-bricant introduced into said chamber to escape therefrom to maintain circulation of the lubricant through said chamber for removing of heat from said tube moving from said sink die to said draw die.

7. In tube drawing, the combination of a die holder, a first die carried by the holder in a first plane for sinking to reduced outer diameter a metal tube of initial outer diameter as it is drawn through the first die, a second die carrier by the holder in a second plane parallel to said first plane and inaxial alignment with said first die for drawing to reduced thickness the wall of the tube from said first die as it is drawn through the second die, said holder and first die having opposed surfaces spaced and arranged to permit lateral movement of the first die in said first plane relative to the holder so as to permit the first die if not correctly aligned with the second die to axially align itself with said second die under the pull exterted by said tube on said first die as the tube is drawn therethrough, said dies having throats engaged by the outer wall of the tube as it is drawn through the said dies, spacing means spacing said throats longitudinally of the said tube to provide an annular space around .the tube between the die throats, inclosing means about said annular space to provide with the outer wall of the tube an enclosed chamber about the tube intermediate said die throats, conduit means extending into said chamber for introducing liquid under pressure thereto for covering the said tube with said liquid prior to its entry into the throat of said second die, a drawing plug adapted to be located in said tube and within said dies unconnected with external restraint against movement with the tube forwardly from said dies, said plug having a forward por-- the entrance side of said first die to restrain movement of inishing from said greater diameter toward the throat of said first die and internally supporting and slidably engaging the tube as it is drawn into the throat of said first die, said head portion in restraining the head portion of the plug from moving forwardly along with said tube as it is drawn progressively through the said first and second dies fixing the position of said forward portion in the tube relative to said second plane.

8. The combination claimed in claim 7 and in which said plug has a space within the tube and between the forward portion and rearward portion for accommodating material scraped from the inner wall of the tube by the forward portion as the tube is drawn over the same,

and said plug has a vent for permitting said material to escape from said space into the tube rearwardly of said,

rear portion.

9. The combination claimed in claim 7 and including second conduit means at a distance from and opposite of said first-mentioned conduit means for the escape of said liquid from said chamber to permit the liquid to circulate through the chamber around and past said tube for cooling the same.

10. In tube drawing apparatus the combination of a die holder having a socket, a plurality of dies positioned in said socket and carried by the holder, the said dies hav-' ing tube-accommodating throats arranged to be in axial alignment and being arranged so that a tube being drawn therethrough first enters the throat of the first die at the first end of the holder and last enters the throat of the last die at said opposite end of the holder, the outer wall of said first die being so dimensioned in relationship to the inner wall of said socket of the die holder that the said first die may shift laterally relative to the axis of the of said last die, spacing means carried by the holder for spacing the said throats in an axial direction to expose the outer wall of the tube intermediate said die throats, chamber means carried by the holder providing a confined chamber around the exposed tube between said die throats, entrance port means communicating with said chamber means for introduction of liquid into said chamber to apply the liquid to said exposed tube wall prior to entering the throat of said last die, and a drawing plug floatingly carried in the tube and within said dies, said plug being unconnected with external means for restraining movement of the plug with the tube as it is drawn through said dies, said first die and said plug having cooperating opposed faces for reducing the outer diameter of the tube as it is drawn through the first die while resisting the movement of the plug through the dies as the tube is drawn therethrough, said first die and said plug on the entrance side of said first die having cooperating opposed walls extending radially outward from the said respective opposed surfaces of the said first die and plug, said opposed walls restraining axial movement of the plug through both said dies with said tube during the drawing thereof, said last die and said plug having cooperating opposed faces for further reducing the outer diameter of p the tube and the wall thickness thereof :as the tube is suc-.

cessively drawn therethrough, the position of said plug along the axis of said first die relative to a plane through the first die normal to said axis being determined by the said opposed walls restraining axial movement of said plug along said axis.

11. The combination claimed in claim 10 and including a limited-escape port means communicating with said chamber means for maintaining said liquid in said chamher means under pressure and permitting some circulation of the liquid through the chamber means.

112. The combination claimed in claim 10 and including material-collecting means and vent means carried by said plug for collecting in the tube and around the plug material scraped from the inner wall of the tube by the face of the plug cooperating with the opposed face of said last die and venting the collected material into the tube rearwardly of the plug to avoid passage of the material forwardly with the tube between the tube and the face of the plug cooperating with the opposed face of said last die.

13. In tube drawing apparatus the combination of a die holder, a pair of annular dies in consecutive arrangement held by said dies with the throats of the dies in substantial axial alignment, the first of said dies being positioned to first meet the tube being drawn to sink the same to reduced outer diameter upon being drawn through the throat of the first die, a second of said dies being positioned to receive the tube from the first die and to further reduce the outer diameter of the tube as it is drawn through the throat of the second die, a drawing plug of the floating type positionable in said tube Within the dies for cooperating with the dies in effecting said reduction, said plug within said second die coacting therewith in sliding engagement with the tube to reduce and size the tube wall thickness, said plug adjacent the entrance to said first die being dimensioned to resist forward movement of the plug through the first die with the tube as the tube is drawn therethrough in sliding engagement with the plug, the said resistance to movement of the plug through the first die determining the position of the plug along the axis of the second die relative to a plane through the second die normal to said axis, the faces of the respective dies engaging the outer wall of the tube as it is drawn successively therethrough being spaced longitudinally of the tube to expose the outer wall of the tube therealong, said holder including enclosed chamber means between said dies and around the exposed outer tube wall, and liquid-treating means carried by the holder for applying liquid within said enclosed chamber means to said exposed outer tube wall between said spaced faces of the respective dies and along the length of said exposed outer tube wall prior to the entry of the tube into said second die.

14. The combination claimed in claim 13 and in which said liquid-treating means includes means for confining the said liquid in said enclosed chamber means under pressure around said exposed outer tube wall.

15. The combination claimed in claim 13 and in which said liquid-treating means includes means for causing said liquid to circulate through said enclosed chamber means about said exposed outer tube wall for cooling the same.

16. The combination of a pair of spaced axially aligned dies through which a tube is progressively drawn through the successive dies and having tube-engaging surfaces spaced apart in an axial direction to expose the outer wall of the tube intermediate of said spaced surfaces, wall means extending between said spaced surfaces outwardly of the tube to provide a chamber around the exposed outer wall of the tube, means for introducing liquid into said chamber for bathing the exposed outer wall of the tube with said liquid prior to entry of the tube into the last of said successive dies, and plug means unconnected with external restraint against forward axial movement through said dies with said tube, said plug means having a first portion positionable within, and having a maximum diameter related to the minimum bore diameter of, a successor die of said successive dies to cooperate therewith at that location for the reduction of the tube wall, said die means having a second portion at a fixed distance from said first portion, said second portion having a maximum diameter related to the minimum bore diameter of an initial die of said successive dies to restrain the plug means against forward axial movement with the tube relative to the respective planes through said dies normal to the axis thereof, the axial position of said second portion relative to said plane of the initial die as restrained by said second portion determining the position of said first portion relative to said plane of the successor die.

17. The combination of a plurality of successively ar ranged tube drawing dies in axial alignment having successively smaller bore diameters for successively reducing to a greater degree the outer diameter of the tube and the thickness of the tube wall, the successive die bores being spaced apart longitudinally of the tube to expose the exterior wall of the tube, wall means bridging the spaced successive bores radially outward of the tube to provide with said tube a confined annular chamber, means for introducing liquid under pressure into said chamber to maintain liquid upon the exposed tube, and a floating plug unconnected with external means for restraining axial movement with the tube and adapted to be-positioned in said tube at said dies, said plug having a nose portion adapted to be positioned within the die of smaller bore diameter of said plurality of dies and having a diameter relative to said smaller bore diameter for cooperating with said die of smaller bore diameter in the reduction of the thickness of the tube wall as the tube is drawn forwardly through said dies, said plug having an enlarged head portion greater in diameter than the bore diameter of the die of larger bore diameter of said plurality of dies to cooperate with said die of larger bore diameter in preventing forward axial movement of said enlarged head portion through the die of larger bore diameter, the said prevention of forward axial movement of said enlarged head portion holding the said nose portion in position within said die of smaller bore diameter.

18. The combination of a die holder, a first die and a second die carried by the holder in successive arrangement with the throats of the dies in substantial axial alignment, spacing means carried by the holder for spacing the die throats apart in an axial direction to expose the outer wall of the tube intermediate the respective die throats, said dies and spacing means forming with said outer tube wall an annular chamber, port means communicating with said annular chamber for introducing a lubricant-coolant liquid into said annular chamber for cooling and lubricating the outer tube wall intermediate the die throats, and a plug floatingly carried within said tube radially inward of the second of said dies to cooperate therewith in the reduction and sizing of the tube wall through said second die, and restraining means connected to said plug and extending axially thereof to the entry side of said first die to cooperate therewith in restraining axial movement of the plug with the tube from within said first die, said restraining means being unconnected to means external of said tube and extending radially on said entry side of said first die sufficiently to resist forward axial movement of the plug with said tube relative to said dies, the location of the plug in said second die being determined by the said restraining means.

19. The combination of first die means for sinking a metal tube to reduce the outer diameter thereof, second die means for reducing the wall thickness of the tube after leaving the first die means,-said first and second die means being arranged in series along a reference line to position the first die means at a location to meet and reduce the tube moving axially along said reference line into the first die means and to position the second die means at a location at an axial distance from the first die means to meet and reduce the tube moving along said reference line into the second die means, said first die means having a bore diameter substantially less than the diameter of the tube prior to entry therein so as to substantially sink or reduce the outer diameter of the tube as it is drawn therethrough, said second die means having a bore diameter substantially less than the bore diameter of said first means, drawing plug means adapted to be positioned in said tube to float Within the tube as it is drawn through the first and second die means for cooperating with the first and second die means, said plug means having a rearward portion dimensioned for coacting with said first die means at said first location in the said sinking or reduction of the outer diameter of the tube and in restraining of the plug means from moving through the die means with said tube, said plug means having a forward portion dimensioned for coacting with the second die means at said second location in reducing the wall thickness of the tube as it is drawn through the second die means, the positioning of the forward portion relative to said second location being dependent on the said restraint provided by said rearward portion, and confined chamber means positioned between said first and second die means including the outer wall of said tube between said first and second die means, said chamber means being adapted to accommodate a liquid for bathing therewith the said outer wall of the tube prior to its entry into said second die means.

20. The combination claimed in claim 19 and said plug means having material-collecting means for collecting rearwardly of the forward portion material scraped by the forward portion from the inner wall of the tube,

12 said collecting means being located internally of the tube intermediate of the first and second die means and radially inward of the said chamber means, and said plug means having vent means for permitting the rearward escape of material from the collecting means prior to movement of the tube into the second die means.

References Cited by the Examiner UNITED STATES PATENTS 2,203,751 6/1940 Simons 72-282 2,428,474 10/ 1947 Snively 72283 3,006,460 10/ 1961 Poncar 7240 3,155,229 11/1964 Lackinger 72-283 3,169,635 2/1965 Prindle 72-283 3,213,663 10/1965 Coan 72-282 FOREIGN PATENTS 522,161 4/1931 Germany.

274 1/ 1887 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner. 

1. APPARATUS FOR THE DRAWING OF A METAL TUBE FROM AN INITIAL SIZE TO REDUCED SIZE COMPRISING THE COMBINATION OF A FIRST DIE, THE THROAT OF SAID FIRST DIE HAVING AN INTERNAL DIAMETER SIZE TO REDUCE THE EXTERNAL DIAMETER OF SAID TUBE OF INITIAL SIZE AS THE TUBE IS DRAWN THERETHORUGH, A SECOND DIE, THE THROAT OF SAID SECOND DIE HAVING AN INTERNAL DIAMETER LESS THAN THE INTERNAL DIAMETER OF SAID FIRST DIE THROAT TO FURTHER REDUCE THE EXTERNAL DIAMETER OF SAID TUBE OF INITIAL SIZE, A HOLDER FOR HOLDING SAID DIES IN ALIGNMENT WITH SAID SECOND DIE FOLLOWING SAID FIRST DIE IN THE ORDER OF TRAVEL OF THE TUBE BEING DRAWN THERETHROUGH, THE THROATS OF SAID DIES BEING SPACED FROM EACH OTHER TO PROVIDE AN OUTER ANNULAR SPACE LONGITUDINALLY OF SAID TUBE AND AROUND THE EXTERIOR OF THE TUBE BETWEEN THE DIE MOUTHS, MEANS FOR INTRODUCING FLUID LUBRICANT INTO SAID OUTER ANNULAR SPACE TO APPLY THE SAME TO THE EXTERIOR OF THE TUBE FOR LUBRICATING THE SAME PRIOR TO ENTERING THE THROAT OF THE SECOND DIE, AND A DRAWING PLUG POSITIONED IN SAID DIES AND CONCENTRICALLY OF SAID THROATS TO BE FLOATINGLY DISPOSED IN THE TUBE BEING DRAWN FORWARDLY ALONG THE COMMON AXIS OF SAID THROATS, SAID PLUG HAVING A REARWARD PORTION HAVING A MAXIMUM EXTERNAL DIAMETER OF SIZE SO RELATED TO THE INTERNAL DIAMETER OF THE FIRST DIE THROAT AS TO RESIST BEING PULLED FORWARDLY ALONG SAID COMMON AXIS THROUGH THE FIRST DIE WITH THE TUBE BEING DRAWN, SAID REARWARD PORTION BEING UNCONNECTED TO EXTERNAL OR OTHER RESTRAINT AGAINST AXIAL MOVEMENT RELATIVE TO SAID DIES AND BY SAID RESISTANCE TO BEING PULLED THROUGH SAID FIRST DIE DETERMINING THE AXIAL LOCATION OF SAID REARWARD PORTION RELATIVE TO SAID FIRST DIE, SAID PLUG HAVING A FORWARD PORTION POSITIONABLE WITHIN THE SECOND DIE THROAT AND WITHIN THE TUBE BEING DRAWN, SAID FORWARD PORTION SUPPORTING THE TUBE WALL AND SIZING THE INTERNAL DIAMETER OF THE TUBE DRAWN THROUGH THE SECOND DIE, SAID PLUG HAVING AN INTERMEDIATE PORTION JOINING SAID FORWARD AND REARWARD PORTIONS AND HAVING A DIAMETER LESS THAN THE DIAMETER OF SAID FORWARD PORTION TO PROVIDE AN INNER ANNULAR SPACE WITHIN THE TUBE BETWEEN SAID FORWARD AND REARWARD PORTIONS, SAID INTERMEDIATE PORTION DETERMINING THE AXIAL DISTANCE BETWEEN SAID FORWARD PORTION AND REARWARD PORTION OF THE PLUG TO DETERMINE THE LOCATION OF THE SAID FORWARD PORTION OF THE PLUG RELATIVE TO SAID SECOND DIE IN ACCORDANCE WITH THE LOCATION OF THE REARWARD PORTION OF THE PLUG AS DETERMINED BY THE SAID RESISTANCE TO BEING PULLED FORWARDLY THROUGH SAID FIRST DIE, SAID REARWARD PORTION HAVING A VENT EXTENDING THEREALONG FOR PREMITTING MATERIAL SCRAPED FROM THE INNER WALL OF THE TUBE BY THE PLUG AND ACCUMULATING IN SAID INNER ANNULAR SPACE TO ESCAPE REARWARDLY OF THE PLUG. 